By way of example, installation switching devices of this generic type may be circuit breakers, residual current devices, motor protective switches or selective main line circuit breakers. A tool by means of which pressure is exerted on the spring leaf is normally required in order to open the spring-loaded terminal. Although the spring-loaded terminal arrangement is then itself of very simple design, an additional control opening must, however, be provided in the housing of the installation switching device, and handling is complicated because of the tool which is required for insertion and removal of the connecting conductor.
In order to allow a connecting conductor to be connected to, and removed again from, spring-loaded terminals of this generic type without a tool, it is necessary for the spring-loaded terminal arrangement to have a spring operating means which an operator can use to open the spring-loaded terminal when required, by pushing on the spring leaf. The terminal is closed automatically because of the resetting spring force of the spring leaf, when the pressure is removed from the spring leaf.
EP 1 213 791 B1 discloses a spring-loaded terminal arrangement which has an operating lever for the spring leaf, having a spring leaf of the cage type which forms a loop with a triangular profile at the rounded angles, with the two end sections being aligned precisely at right angles to one another, and having an electrically conductive terminal to which the first end section of the spring leaf is fitted, and with an opening passing through the leaf. The operating lever for the leaf is mechanically connected to the terminal, and guide means for the operating lever are fitted to the terminal. The guide means make it possible to keep the lever in constant contact with the spring leaf. When no pressure is applied to the spring leaf, the lever rests on the culmination section of the spring leaf.
In this case, the advantage of operability without the use of tools is obtained at the expense of the disadvantage of complicated design of the spring terminal arrangement.